The metadata below describe the original scanning. Follow the "All Files: HTTP" link in the "View the book" box to the left to find XML files that contain more metadata about the original images and the derived formats (OCR results, PDF etc.). See also the What is the directory structure for the texts? FAQ for information about file content and naming conventions.
"The substance of the following pages was delivered, in the form of lectures, to the members of the Philosophical institution of Edinburgh, in the months of March and April, 1858."--Prefatory note